A flood is a type of weather.Floods form when it rains way to much or if a river over flows.floods can also form from the sea.Flood Types, Flash Flood: when the water of a flood is really fast. Overflow of major rivers: the water goes over banks and goes all over the terrain both the flow speed and the rising speed comparatively low.ponding, pluvial flooding or water logging: water lays on top of the ground because of all the rain that comes down and it will not dry fast enough.The Causes of a flood: Storm, Heavy rainfall, or the melting of ice or snow.